The information in this document is only for devices that run Cisco IOS
software. The c7500 example with multiple CPUs uses Cisco IOS Software Release
12.0(22)S3.

The information in this document was created from the devices in a
specific lab environment. All of the devices used in this document started with
a cleared (default) configuration. If your network is live, make sure that you
understand the potential impact of any command.

Critical router functions, like routing protocol processing and process
packet switching, are handled in memory and share the CPU. Thus, if CPU
utilization is very high, it is possible that a routing update cannot be
handled or a process-switching packet is dropped. From the
CISCO-PROCESS-MIB,
the
cpmCPUTotal5minRev
MIB object value reports the percentage of the processor in use over a
five-minute average.

The
cpmCPUTotal5minRev
MIB object provides a more accurate view of the performance of the router over
time than the MIB objects
cpmCPUTotal1minRev
and
cpmCPUTotal5secRev.
These MIB objects are not accurate because they look at CPU at one minute and
five second intervals, respectively. These MIBs enable you to monitor the
trends and plan the capacity of your network. The recommended baseline rising
threshold for
cpmCPUTotal5minRev
is 90 percent. Depending on the platform, some routers that run at 90 percent,
for example, 2500s, can exhibit performance degradation versus a high-end
router, for example, the 7500 series, which can operate fine.

cpmCPUTotal5secRev
(.1.3.6.1.4.1.9.9.109.1.1.1.1.6): The overall CPU busy percentage in the last
five-second period. This object deprecates the object cpmCPUTotal5sec and
increases the value range to (0..100).

cpmCPUTotal1minRev
(.1.3.6.1.4.1.9.9.109.1.1.1.1.7): The overall CPU busy percentage in the last
one-minute period. This object deprecates the object cpmCPUTotal1min and
increases the value range to (0..100).

cpmCPUTotal5minRev
(.1.3.6.1.4.1.9.9.109.1.1.1.1.8): The overall CPU busy percentage in the last
five-minute period. This object deprecates the object cpmCPUTotal5min and
increases the value range to (0..100).

This table shows the new MIBs and their objects beside the old MIBs and
objects they replace:

The percentage of CPU time at interrupt level (fast-switched
packets), over a five-second period. If you take the difference between the
first and second, you arrive at the five-second percentage the router spends at
the process level. In this case, the router spends one percent at the process
level over the last five seconds (process- switched packets - No MIB variable).

The CPU utilization over the last minute [also available through the
object avgBusy1
(.1.3.6.1.4.1.9.2.1.57)]

When you poll CPU utilization variables and any other SNMP variables,
the actual CPU utilization is affected. Sometimes, the utilization is 99
percent when you continuously poll the variable at one-second intervals. It is
an overkill to poll so frequently, but take into consideration the impact to
CPU when you determine how frequently you want to poll the variable.

This implies that the IOS device must support both
CISCO-PROCESS-MIB
and
ENTITY-MIB
for you to be able to retrieve relevant information about CPU utilization. The
only case where you do not need to have or use
ENTITY-MIB
is when you only have a single CPU.

Monitor the use of multiple CPUs in the 7500 chassis (RSP and two
VIPs). The same applies to GSR linecards. Use Cisco IOS Software Release
12.0(22)S3 or later when you poll c7500 or GSR for these values. Be aware of
the related bugs:
CSCdw52978
(registered customers only)
,
CSCdp17238
(registered customers only)
.

Poll cpmCPUTotal5min
(.1.3.6.1.4.1.9.9.109.1.1.1.1.5) to get "overall CPU busy
percentage in the last 5 minute period" for all CPUs in the chassis. The output
shows that the 7507 device has three CPUs, utilized for 10%, 1%, and 2% during
last 5 minutes.

In order to identify the particular card to which each physical
entry is related, poll correspondent entPhysicalName
(.1.3.6.1.2.1.47.1.1.1.1.7) entry, with the exact indexes 9, 25,
28 from Step 2, as a last digit. You see that RSP is utilized for 10%, and VIPs
in slots 4 and 6 are utilized for one and two percent.

Catalyst 5000 LANE Module does not have its own IP address. Therefore,
you must use the IP address of Catalyst supervisor along with community string
indexing. For example, if your LANE card is in slot 6 of your catalyst and your
community string is public, use community string "public@6" and send the SNMP
request to the IP address of the supervisor module. Refer to
SNMP
Community String Indexing for more information.

Note: If you do not specify the module number in the community, you receive
data corresponding to the first LANE module in the Catalyst chassis.